Microwave cooking apparatus

ABSTRACT

An eye-level microwave oven having a set of cooking burners disposed therebelow includes a ventilation duct extending vertically from a bottom chamber of the apparatus to the microwave oven. The duct may terminate at either the bottom or the back of the microwave oven.

United States Patent 1191 Miller et al.

[111 3,818,171 June 18, 1974 MICROWAVE COOKING APPARATUS Inventors: Matthew S. Miller, Holliston; Paul F. Hal-hen, Milford, both of Mass.

Assignee: Sage Laboratories, Inc., Natick,

Mass.

Filed: May 26, 1972 Appl. No.: 257,185

US. Cl 219/1055, 126/21 A, 312/236 Int. Cl. H05b 9/06 Field of Search 219/1055, 399, 400;

References Cited UNITED STATES PATENTS H1969 Perry 126/21 A 3,654,417 4/1972 Javes et a1. .Q 219/1055 Primary Examiner-J. Truhe Assistant Examiner-Hugh D. Jaeger [57] ABSTRACT An eye-level microwave oven having a set of cooking burners disposed therebelow includes a ventilation duct extending vertically from a bottom chamber of the apparatus to the microwave oven. The duct may terminate at either the bottom or the back of the microwave oven.

7 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION Some commercially available cooking apparatus includes a set of cooking burners which may be gas or electric burners, and an eye-level oven disposed thereabove. The eye-level oven is also operated typically by either gas or electricity.

In accordance with the present invention, the conventional eye level oven is replaced by a microwave oven of approximately the same size, and disposed above the cooking burners of the apparatus. The microwave oven is powered by a magnetron, or the like. The magnetron may have a maximum allowable operating temperature on the order of 235 F, and thus if the magnetron of the microwave oven is not properly ventilated continuous operation of the oven is not possible when heat is being generated therebelow from the conventional cooking burners.

In a commercial microwave oven, there is generally no heat generated below the oven, and the oven is not normally confined in a small space. However, the eyelevel microwave oven, which is primarily meant for use in a dwelling place, has heat generated therebelow and is also usually disposed against a wall. Thus, the usual ventilation techniques used in commercial microwave ovens do not provide adequate magnetron cooling in the eye-level microwave oven application.

Accordingly, one important object of the present invention is to provide an improved microwave cooking apparatus including an eye-level microwave oven.

Another object of the present invention is to provide a microwave cooling apparatus in accordance with the preceding object and including ventilation means coupled to the microwave oven for cooling the energy source of the oven even when excessive heat is being generated below the oven. The energy source or magnetron must be suitably cooled so that its temperature is maintained below a predetermined shut-off temperature thereby providing continuous operation of the microwave oven under virtually all operating conditions.

A further'object of the present invention is to provide a microwave cooling apparatus in accordance with the preceding objects wherein a conventional eye-level oven can be used and easily adapted for microwave cooking.

SUMMARY OF THE INVENTION To accomplish the foregoing and other objects of the present invention, there is provided a cooking apparatus having a typical set of cooking burners which may be either gas or electric operated, and a microwave oven disposed above and spaced from the cooking burners. In accordance with one aspect of the present invention, the cooking apparatus has an enclosed chamber at the bottom thereof, and there is provided a ventilation duct preferably vertically arranged, and extending from the bottom chamber of the apparatus to the microwave oven. In one embodiment of the invention the ventilating duct terminates at the bottom of the microwave oven and in an alternate embodiment the duct terminates into the back of the microwave oven. I

In a preferred embodiment, the duct has a rectangular cross section of a first area and the opening into the microwave oven is dimensioned having a second area,

wherein the first area is preferably larger than the second area for providing adequate air flow. The blower that is provided in the microwave oven for circulating the air adjacent the magnetron, or the like, has an intake aperture that is preferably circular and should have a cross section no larger than the said second area.

BRIEF DESCRIPTION OF THE DRAWINGS Numerous other objects, features and advantages of the invention will now become apparent upon a reading of the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a microwave cooking apparatus constructed in accordance with the principles of the present invention;

FIG. 2 is a side view of the apparatus of FIG. 1 partially in cross section showing one embodiment for the ventilation duct;

FIG. 3 is a back view of the cooking apparatus of FIG. 1;

FIG; 4 is a perspective view of the microwave oven section of the cooking apparatus of FIG. 1 partially cut away to show the compartment containing the energy source for the oven; and

FIG. 5 is a side view similar to the one shown in FIG. 2 partially in cross section of another embodiment of the ventilation duct of the present invention.

DETAILED DESCRIPTION Referring now to the drawings, and in particular to FIG. 1, there is shown a perspective view of a cooking range that is basically of conventional design but includes a microwave oven 12 in place of the conventional eye-level oven. The range includes cooking bu rners I4 which may be either electric, gas or the like, burners and their associated controls 16. The range is basically constructed of sheet metal, may have a baked enamel finish and may include a storage area in the bottom portion 18 of the range.

An upwardly. extending intermediate portion 20 interconnects the bottom portion 18 with the rear of the microwave oven 12. The microwave oven preferably has an insulating sheet 22 disposed therebelow to provide a limited amount of insulation between the heat generated from the burners l4 and the microwave oven itself.

The range 10 is typically constructed as depicted in the cutaway section in FIG. 1, with the side walls 24 extending rearwardly to form a back cavity 26 (see also FIG. 3). As indicated in FIG. 2, the bottom portion 18 is also constructed so that there is an open bottom chamber 28 that forms an enclosed chamber when the range is supported on a floor or the like. This bottom chamber 28 is vented at the front vent 30. Referring now to FIGS. 2 and 3, there is shown respective side and back views of the cooking range indicating the position for the vertical ventilating duct 32. Duct 32 connects from the bottom chamber 28 through an opening 34 in the back wall 36 defining the chamber 28. The

duct 32 may be constructed of sheet metal and its upper end terminates in an opening 38 in the back wall 40 of the microwave oven. Thus, the bottom chamber 28 is a source of relatively cool input air coupled from input vent and the vertical duct 32 carries this relatively cool air to the microwave oven 12.

, Referring now to FIG. 4 there is shown a perspective view of the microwave oven l2pa'rtially cutaway to diagrammatically show some of the internal components comprising the oven. The oven comprises a bottom insulating plate 22, a top plate 44 and an intermediate plate 46. The oven also comprises a front door 48 and a number of vertically extending walls 50 which define an oven cooking area 52 and a component storage area The space provided between top wall 44 and intermediate wall 46 defines an output plenum chamber 45 having an output vented opening 56 and an input opening 58 which com'municates'with the blower 60 in the area 54. Area 54 also contains a magnetron 62 or the like and means 64 which may be a wave guide for coupling the energy from the magnetron to the cooking cavity 52.

The blower 60 may be of conventional design and includes a circulating fan 66 having an input port 68. FIG. 4 also shows the opening 38 in the back wall 40 which terminates the top end of the vertical duct 32.

When the oven was operated without the use of a vertical duct and with the use of a rear input port, there was not sufficient cooling provided for the magnetron, and thus the temperature limit switch associated therewith caused intermittent operation of the magnetron. Typically, the magnetron should not be operated at its coolingfins in excess of approximately 235 F. With the use of a vertical duct interconnecting to the bottom chamber 28 sufficient cooling was provided to enable continuous operation of a magnetron. Also, this operation was tried with all of the burners 14 on which would be the worst case condition.

In accordance with'one aspect of the' present invention, it was discovered that the cross sectional area A1 of the duct 32 should be larger than the cross section of the opening 38. In 'oneembodiment the ventilation duct 32 has an 8 X 1 1/2 inch cross section and the opening 38 has a 7 X 1 H2 inch opening. Alternatively, the area Al should not be made too much larger than the area A2 as this would decrease the velocity of the air moving up the vertical duct 32. The air should be drawn up the duct at approximately 80 cu. ft. per minute. It is also preferred that the opening 34 in the bottom be slightly larger in area than the area Al. The dimensions of this opening may be 8 inches by 2 inches for example. i

In accordance with a further aspect of the present invention, it was found that the opening 38 in the rear wall 40 of the microwave oven should not be any smaller than the cross sectional area A3 of the input port 68 of the blower 60. In one embodiment the diameter of the input port 68 is 2 3/4 inches and the area A3 is approximately 9 sq. in. The area of opening 38 is approximately 10 H2 sq. in. The air passes from the output port 58 of the b1ower60 and is vented through vents 56 preferably in the front, top portion of the microwave oven FIG. 5 shows an alternate arrangement for the vertical duct 32. The duct 32 couples from the bottom chamber 28 to the bottom of the microwave oven andthe opening terminating the' top of the vertical duct 32 may be the same size as opening 38 shown in FIG. 4. Alternatively, the top end of duct 32 may extend through bottom insulated wall 22 andterminate slightly above this wall internal of the oven. With the duct in this position, the cooling is approximately the same as discussedv hereinbefore with reference to FIGS. l-4.

Having described a limited number of embodiments of the present invention, it should now be obvious that numerous other embodiments will fall within the spirit and scope of the present invention which is defined by the appended claims. i

What is claimed is: l. A cooking apparatus comprising; a bottom section having a plurality of upright walls, a back wall and a bottom plate defining a chamber having'at least one port for carrying air from outside the apparatus to the chamber, said chamber being a source of relatively cool air, a top section including a microwave oven having electrical components including a magnetron, and

a circulating blower with an air intake port, means intermediate the top and bottom sections for structurally interconnecting the top and bottom sections with the top section disposed at normal eye level,v and a ventilation duct that continuously extends from said bottom chamber to said microwave oven, said microwave oven having an opening for receiving the top end of the ventilation duct and said bottom section having a rear wall defining in part the chamber, said rear wall having an opening for receiving the bottom end of the ventilation duct, said ventilation duct having a cross-sectional area smaller than the cross-sectional area of the opening I from the rear wall defining the bottom chamber.

2. The apparatus of claim 1 wherein the crosssectional area of the duct is larger than the crosssectional area of the opening in the microwave oven.

3. The apparatus .of claim 2 wherein the blower and duct are constructed to pass air at a rateof approximately cubic feet per minute.

4. The apparatus of claim 3 wherein the crosssectional area of the intake port of the blower is smaller than the cross-sectional area of the opening in the microwave oven to which the duct is coupled.

5. The apparatus of claim 4 wherein said duct has a rectangular cross-section.

6. The apparatus of claim 5 wherein said microwave oven has an output air vent and means defining an output plenum chamber for receiving area from the blower and exiting air via the output air vent.

7. The apparatus of claim 6 wherein said bottom chamber, duct and blower are for conveying air to the microwave oven for the purpose of cooling the components therein, said air flow being continuous from said bottom chamber to said microwave oven. 

1. A cooking apparatus comprising; a bottom section having a plurality of upright walls, a back wall and a bottom plate defining a chamber having at least one port for carrying air from outside the apparatus to the chamber, said chamber being a source of relatively cool air, a top section including a microwave oven having electrical components including a magnetron, and a circulating blower with an air intake port, means intermediate the top and bottom sections for structurally interconnecting the top and bottom sections with the top section disposed at normal eye level, and a ventilation duct that continuously extends from said bottom chamber to said microwave oven, said microwave oven having an opening for receiving the top end of the ventilation duct and said bottom section having a rear wall defining in part the chamber, said rear wall having an opening for receiving the bottom end of the ventilation duct, said ventilation duct having a cross-sectional area smaller than the cross-sectional area of the opening from the rear wall defining the bottom chamber.
 2. The apparatus of claim 1 wherein the cross-sectional area of the duct is larger than the cross-sectional area of the opening in the microwave oven.
 3. The apparatus of claim 2 wherein the blower and duct are constructed to pass air at a rate of approximately 80 cubic feet per minute.
 4. The apparatus of claim 3 wherein the cross-sectional area of the intake port of the blower is smaller than the cross-sectional area of the opening in the microwave oven to which the duct is coupled.
 5. The apparatus of claim 4 wherein said duct has a rectangular cross-section.
 6. The apparatus of claim 5 wherein said microwave oven has an output air vent and means defining an output plenum chamber for receiving area from the blower and exiting air via the output air vent.
 7. The apparatus of claim 6 wherein said bottom chamber, duct and blower are for conveying air to the microwave oven for the purpose of cooling the components therein, said air flow being continuous from said bottom chamber to said microwave oven. 